Soil sample core system

ABSTRACT

A soil sample core system includes an outer cylinder having first and  sec ends; a sample tube for sliding within the outer cylinder; a tip sleeve mounted to the first end of the outer cylinder; a push pipe which may be mounted to the second end of the outer cylinder to prevent the sample tube from sliding out of the second end; a tapered tip which may be selectively extended out of the tip sleeve and which may be selectively retracted into the push pipe; an end cap having a threaded bore which may be mounted to the second end of the outer cylinder in place of the push pipe; a threaded shaft threaded in the threaded bore; a piston rotatively mounted to one end of the threaded shaft for sliding within the outer cylinder; and a torque transmitting element mounted to the other end of the threaded shaft for transferring torque to thread the shaft through the threaded aperture.

BACKGROUND OF THE INVENTION

The present invention generally relates to the field of ground soilcoring equipment, and more particularly, to a soil sample core system inwhich a screw driven rotatable piston is used to drive a soil sampletube out of the system without disturbing the soil sample.

Many commercially available soil sampling tools usually consist of anouter cylinder and one or more serially stacked inner cylinders that fitwithin the outer cylinder. The tools are pushed into the ground byvarious means. The soil sample is collected inside the inner cylinder(s)which are usually thin wall tubes. The outer cylinder is relativelythick walled and acts as the strength member to which force is appliedto push the tool through the soil. The inner tubes may also be "split"tubes, so that the tube can be "peeled" away from the soil sample.

A problem with soil sampling tools is that soil is also collected in theannulus formed between the outer and inner cylinders. If the soil isdense, abrasive, and compacted within the annulus, the inner tubes maybecome lodged or jammed so that they cannot easily be removed from theouter cylinder without disturbing the soil samples. When this happens,the jammed tubes need to be "hammered" out of the outer cylinder.However, such hammering generally disturbs, and in some cases destroys,the soil sample.

Therefore, a need exists for a tool for collecting soil samples whichallows the soil samples to be removed without being disturbed.

SUMMARY OF THE INVENTION

The present invention provides a soil sample core system for collectingsoil samples which allows the soil samples to be removed from the toolwithout being disturbed. A soil sample core system comprises an outercylinder having first and second ends; a sample tube for sliding withinthe outer cylinder; a tip sleeve mounted to the first end of the outercylinder; a push pipe which may be mounted to the second end of theouter cylinder to prevent the sample tube from sliding out of the secondend; a tapered tip extended out of the tip sleeve and which may beselectively retracted into the push pipe; an end cap having a threadedbore which may be mounted to the second end of the outer cylinder inplace of the push pipe; a threaded shaft threaded in the threaded bore;a piston rotatively mounted to one end of the threaded shaft for slidingwithin the outer cylinder; and a torque transmitting element mounted tothe proximal end of the threaded shaft for transferring torque to threadthe shaft through the threaded aperture and causing the piston to drivethe sample tube out of the outer cylinder.

The system uses the mechanical advantage of a threaded shaft and pistonto smoothly and gently push the soil sample tubes out of the cylinder.The system is portable, simple, and may be motorized. The piston andshaft may each have a conically shaped surface to provide a bearinginterface that facilitates rotation of the piston with respect to thethreaded shaft so that the piston does not apply any torque to the soilsample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of a soil sample core systemembodying various features of the present invention which shows thetapered tip locked in the extended position.

FIG. 2 is a cross-sectional view of the soil sample core system showingthe tapered tip retracted in the push pipe.

FIG. 3 shows the sample tube ejection assembly mounted to the outercylinder and the piston engaged to push the soil filled inner tubes outof the outer cylinder.

FIG. 4 is a cross-sectional view showing the land at the periphery ofthe piston engages the sample tube.

FIG. 5 shows an end view of the torque transmitting element mounted tothe proximal end of the threaded shaft.

FIG. 6 shows the torque transmitting element welded to the shaft end.

FIG. 7 is a cross-sectional view of the soil sample core system showinghow the piston drives the sample tubes from the outer cylinder.

Throughout the figures, like references refer to like elements.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, the present invention provides a soil samplecore system 10 by which subterranean soil samples 32 may be retrievedand then easily ejected from the system without being damaged. Referringto FIGS. 1 and 2, the system 10 incorporates a soil sampling tool 12,such as a Van Den Berg, Inc. MOSTAP sampler 35 PS, ART. No. 060050A)which includes an outer cylinder 20 that houses one or more soil sampletubes 30 (two are shown, for example) stacked in series and aretractable tip 24 extending from one end of the cylinder 20. The outercylinder 20 has first and second threaded ends 21 and 23, respectively,and a through bore 19. A tip sleeve 22 is screwed to the threaded end 21and a push pipe adapter 28 is screwed to the other threaded end 23. Thepush pipe adapter 28 is also threaded (not shown) to receive continuinglinks of push pipe (not shown) that are used to push the tool 12 to theappropriate depth of interest through the soil. The tip sleeve 22selectively holds a retractable conically shaped tip 24 fixedly in placeso that the tip 24 extends from the tip sleeve 22. The tip sleeve 22includes an annular groove 44 formed in its inner surface 25. A plunger27 having radially distributed tapered recesses 29 is positioned withinthe tip sleeve 22 so that when the recesses 29 are aligned with thegroove 44, spherical bearings or balls 26 are held between the groove 44and recesses 29 to secure the conical tip 24 at the end of the outercylinder 20.

Once the soil sampling tool 12 is pushed to a depth of interest, the tip24 may be retracted up inside the tool 12. Retracting the tapered tip 24is accomplished by pulling aft on a cable 34, attached to the plunger27, in the direction of arrow 33, causing the balls 26 to be pushedinwardly out of the groove 44 of the tip sleeve 22. Continued pulling onthe cable 34 causes the tip 24 to be pulled up through the bore 19 ofouter cylinder 20 and into the bore 31 of push pipe adapter 28, as shownin FIG. 2. The tool 12 is now ready to be configured to obtain soilsamples.

As the tool 12 is again pushed through the soil, soil samples 32 enterthe tip sleeve 22 through bore 37 and fill coaxially aligned soil sampletubes 30 having an outer diameter which allows them to smoothly slidewithin bore 19 of the outer cylinder 20. FIG. 2 shows the tip 24retracted within the push pipe adapter 28 and inner tubes 30 filled withsoil samples 32. The tool 12 may then be pulled up to the terrestrialsurface (not shown) so that the soil samples 32 may be retrieved.

In order to configure the soil sample core system 10 so that the soilsample tubes 30 may be ejected from the cylinder 20, the tip sleeve 22and push pipe adapter 28 are removed from the cylinder 20. Then, thesample tube ejection assembly 35, shown in FIG. 3, is mounted to one endof the cylinder 20. The sample tube ejection assembly 35 includes theend cap 36, a threaded shaft 38 which is threaded through the threadedaperture 39 of the end cap 36, and a piston 42. The distal end of theshaft 38 preferably includes a bearing 41, preferably having a conicallyshaped surface which may be made of materials such as steel, bronze,brass, copper alloys, or even plastic. The piston 42 includes a recess50 that provides a bearing surface 52 shaped to fit over the bearing 41so that the piston 42 may freely rotate with respect to the shaft 38,and an annular land 52, shown in FIG. 4, sized to engage the end 56 ofsample tubes 30. Referring also to FIG. 3, the piston 42 may be held inposition at the end of the shaft 38 by, for example, a washer 44 andscrew 46, although other mechanical retaining systems such as internalor external C-rings. The end cap 36 preferably may have outer hex shapeas shown in FIG. 5 so it can be easily tightened onto the cylinder 20. Atorque transmitting element 54, such as a hexagonal nut welded, may bemounted onto the proximal end of the threaded shaft 38, as for exampleby welding, to facilitate rotation of the threaded shaft 38 by theapplication of torque to the element 54. The forward end of the shaft 38may contain a hexagonal recess 48, as shown in FIG. 6, for receiving adrive coupling, not shown, so that the shaft 38 may be rotated by amotor driven tool such as a power drill. To counter the rotation of theshaft 38, the end cap 36 can be held in a vice or with a wrench.

The threaded shaft is fully retracted so that the piston 42 may slideinto the bore 19 of the cylinder 20 and so that the threaded bore 43 ofthe end cap 36 may be screwed to one end of the cylinder 20, whereuponthe soil sample core system 10 is configured as shown in FIG. 3. As thethreaded shaft 38 is rotated by end nut 54, the piston 42 advances inthe bore 19 of the outer cylinder 20 so that the annular land 58 of thepiston 42 butts up against the end 56 of the soil sample tube 30,thereby forcing the soil sample tube(s) 30 out of the open end 45 of thecylinder 20. The distal end of the piston 42 includes a frustrum shaped,or conically tapered surface 60 which allows the piston 42 to becentered against and within the end of the tube 30 as annular land 58 ofthe piston 42 drives the tube 30 out of the outer cylinder 20. Withoutthe tapered surface 60, the piston 42 may not be centered against thetube 30, causing the tube 30 to jam within the cylinder 20. Torqueapplied to the shaft 38 via the torque transmitting element 40 throughthe end cap 36 provides a large mechanical advantage that readily causesthe soil sample tubes 30 to be driven out of the cylinder 20. Althoughthe threaded shaft 38 rotates as it feeds through the end cap 36, thepiston 42 does not rotate with respect to the soil sample tubes 30because the piston 42 is free to rotate about the bearing 41 at the endof the threaded shaft 38. Therefore, the piston 42 does not transfertorque to either the sample tube 30 or soil sample 32. FIG. 7 shows thesoil filled sample tubes 30 being pushed out of the cylinder 20 by thepiston 42 as the threaded shaft 38 is fed through the end cap 36. Afterbeing ejected from the cylinder, the soil sample tubes 30 may be sealedwith standard plastic end caps, not shown, and sent to a laboratory foranalysis. Thus it may be appreciated that the invention provides a soilsample core system by which soil samples may be retrieved without beingcompressed or otherwise disturbed.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

I claim:
 1. A soil sample core system, comprising:a soil sampling coreassembly which includes:an outer cylinder having first and secondcylinder ends; a sample tube which slides within said outer cylinder forretrieving a soil sample as said outer cylinder penetrates subsurfacesoil; a tip sleeve selectively mounted to said first cylinder end ofsaid outer cylinder; a tapered tip which extends out of said tip sleevefor facilitating penetration of said outer cylinder to a depth ofinterest in said subsurface soil, and is retracted through said sampletube and out of said outer cylinder so that soil samples enter saidsample tube upon further penetration of outer cylinder into saidsubsurface soil; and a soil sample retrieving assembly which includes:anend cap having a threaded bore selectively mountable to said first orsecond cylinder end of said outer cylinder when said tip sleeve isdisassembled from said outer cylinder; a threaded shaft threaded in saidthreaded bore and having first and second shaft ends; a pistonrotatively mounted to said second shaft end of said threaded shaft forsliding within said outer cylinder, and having a frustrum shaped surfacefor centering said piston partially in and against said sample tube; anda torque transmitting element mounted to said first shaft end of saidthreaded shaft for transferring torque to said threaded shaft so thatsaid piston drives said sample tube out of said outer cylinder.
 2. Thesoil sample core system of claim 1 wherein;said threaded shaft has afirst tapered bearing at said second shaft distal end; and said pistonhas a second tapered bearing surface for rotatively engaging said firsttapered bearing surface so that said piston may rotate with respect tosaid threaded shaft.
 3. The soil sample core system of claim 1 whereinsaid piston has an annular land for engaging said sample tube.
 4. Thesoil sample core system of claim 1 wherein said torque transmittingelement is a nut.
 5. The soil sample core system of claim 4 wherein saidnut has a recess for receiving a torque driving tool for turning saidthreaded shaft.